Fast paging method, bluetooth system and bluetooth connection method using the same

ABSTRACT

There is provided a fast paging procedure in which a master device repeatedly sends the paging message to a slave device using predetermined channel frequencies, wherein a selection of the predetermined channel frequencies is not calculated or predicted from the slave&#39;s Bluetooth device address. When the master device receives a slave page response message at one frequency among the predetermined channel frequencies, the master device transmits an FHS packet to the slave device at the same frequency in which the slave page response message was received.

BACKGROUND 1. Field of the Disclosure

This disclosure generally relates to the Bluetooth connection, moreparticularly, to a fast and simplified paging procedure to set up aninitial connection between a master and a slave without using estimatedor predicted clock frequencies.

2. Description of the Related Art

In the Bluetooth connection procedure, the page substate is used by themaster to activate and connect to a slave in a page scan substate. Themaster tries to coincide with the slave's scan activity by repeatedlytransmitting the paging message consisting of the slave's device accesscode (DAC) in different hop channels. Since the Bluetooth clocks of themaster and the slave are not synchronized, the master does not knowexactly when the slave wakes up and on which hop frequency. Therefore,the master transmits a train of identical page scan messages atdifferent hop frequencies and listens in between the transmit intervalsuntil it receives a response from the slave.

The conventional initial messaging between a master and a slave is shownin FIGS. 1 and 2. The master calculates 32 hop frequencies using theslave's Bluetooth device address (BD_ADDR), and f(k) and f(k+1) used ina current slot as shown in FIGS. 1-2 are estimated from the slave'sBluetooth clock. This estimate can be derived from timing informationthat was exchanged during the last encounter with this particulardevice, or from an inquiry procedure. With this estimate CLKE of theslave's Bluetooth clock, the master can predict on which hop channel,e.g. f(k), the slave starts page scanning.

It is seen from FIGS. 1 and 2 that when successfully receiving a pagingmessage in step 1, the slave replies a slave page response message tothe master at the response hop frequency f′(k) or f′(k+l) thatcorresponds to the hop frequency f(k) or f(k+1) in which the pagingmessage was received. When successfully receiving the slave pageresponse message in step 2, the master transmits an FHS packet in step 3containing the master's real-time Bluetooth clock, the master's BD_ADDR,the BCH parity bits, and the class of device at a next hop frequencyf(k+1) or f(k+2) determined by frequency hopping.

Conventionally, the page hopping sequence is divided over two pagingtrains A and B of 16 frequencies. Train A includes the 16 hopfrequencies surrounding the current, predicted hop frequency f(k), wherek is determined by the clock estimate CLKE₁₆₋₁₂. The first trainconsists of hops f(k−8), f(k−7), . . . , f(k), . . . , f(k+7). Since themaster does not know when the slave will enter the page scan substate,the master has to repeat this train A for N_(page) times or until aresponse is obtained. When the difference between the Bluetooth clocksof the master and the slave is less than −8×1.28 s or larger than+7×1.28 s, the remaining 16 hops are used to form the new 10 ms train B.Train B consists of hops f(k−16), f(k−15), . . . , f(k−9), f(k+8) . . ., f(k+15). Train B shall be repeated for N_(page) times. If no responseis obtained, train A shall be tried again N_(page) times.

Since alternate use of train A and train B shall be continued until aresponse is received or the timeout is exceeded, slow connection canoccur. That can reduce the user experience in some scenarios.

Accordingly, it is necessary to shorten a time interval required to setup a link in some specific cases such as a quick point-to-point linkreconnection if it is lost during streaming.

SUMMARY

The present disclosure provides a fast paging procedure in the Bluetoothinitial connection without frequency hopping based on estimated hopfrequencies.

The present disclosure provides a paging method of a master deviceperformed in a page substate of the master device for connecting to aslave device in a page scan substate. The paging method includes thesteps of: repeatedly transmitting a paging message sequentially from afirst frequency to a last frequency among multiple predeterminedfrequencies in a fixed sequence; listening a slave page response messagesent at one of the multiple predetermined frequencies; and transmittingan FHS packet at the one of the multiple predetermined frequencies whichthe slave page response message is listened.

The present disclosure further provides a Bluetooth system including amaster device and a slave device. The master device is configured torepeatedly transmit a paging message sequentially at multiplepredetermined frequencies in a fixed sequence. The slave device isconfigured to receive the paging message and respond a slave pageresponse message at one frequency among the multiple predeterminedfrequencies. The master device is further configured to transmit an FHSpacket to the slave device at the same frequency receiving the slavepage response message.

The present disclosure further provides a Bluetooth connection methodbetween a master device and a slave device. The Bluetooth connectionmethod includes the steps of: repeatedly transmitting, by the masterdevice, a paging message sequentially at multiple predeterminedfrequencies to the slave device in a fixed sequence; responding, by theslave device, a slave page response message at one frequency among themultiple predetermined frequencies to the master device; transmitting,by the master device, an FHS packet to the slave device at the samefrequency receiving the slave page response message to the slave device;responding, by the slave device, another page response message at thesame frequency receiving the FHS packet to the master device; andtransmitting, by the master device after receiving the another pageresponse message, a POLL packet using a new hopping sequence determinedaccording to a Bluetooth device address of the master device.

In the present disclosure, a master device sends the paging message at afewer predetermined channel frequencies and a slave device in a pagescan substate only needs to scan said fewer predetermined channelfrequencies, it is able to take a fewer time before entering aconnection state compared to a regular Bluetooth system, whichdetermines a page hopping sequence according to the slave's BD_ADDR.

The fast paging in the present disclosure is referred to a simplifiedpage procedure to facilitate link establishment by using less RFchannels. As fewer predetermined frequencies (i.e. RF channels) areused, a shorter link time is realized and no CLK estimation is requiredanymore. Furthermore, these predetermined frequencies may or may not beselected from the conventional 32 page hopping frequencies in regularBluetooth connection procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, advantages, and novel features of the present disclosurewill become more apparent from the following detailed description whentaken in conjunction with the accompanying drawings.

FIG. 1 is a schematic diagram of the conventional paging procedure inwhich the slave responds to the first paging message.

FIG. 2 is a schematic diagram of the conventional paging procedure inwhich the slave responds to the second paging message.

FIG. 3 is a schematic block diagram of a Bluetooth system adopting afast paging procedure of the present disclosure.

FIG. 4 is a schematic diagram of a paging procedure according to oneembodiment of the present disclosure, in which a slave device respondsto a paging message at a first predetermined frequency.

FIG. 5 is a schematic diagram of a paging procedure according to oneembodiment of the present disclosure, in which a slave device respondsto a paging message at a second predetermined frequency.

FIG. 6 is a schematic diagram of a paging procedure according to anotherembodiment of the present disclosure, in which a slave device respondsto a paging message at a fourth predetermined frequency.

FIG. 7 is a schematic diagram of a paging procedure according to analternative embodiment of the present disclosure, in which a masterdevice does not receive a response message from a slave device.

DETAILED DESCRIPTION OF THE EMBODIMENT

It should be noted that, wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

One objective of the present disclosure is to facilitate the setup of aninitial connection between a master device 31 and a slave device 32 of aBluetooth system without estimating the slave's Bluetooth clockaccording to the Bluetooth device address (BD_ADDR) of the slave device32. FIG. 3 is a block diagram of a Bluetooth system adopting a fastpaging procedure of the present disclosure.

In one non-limiting embodiment, the paging procedure of the presentdisclosure is applied to an application requiring fast Bluetoothconnection. For example, the master device 31 of the present disclosureis operated as both a secondary master (Master 2 shown in FIG. 3) and aprimary slave (Slave 1 shown in FIG. 3). The master device 31 is one ofa pair of Bluetooth earphones, and the slave device 32 is the other oneof said pair of Bluetooth earphones.

FIG. 3 shows that the master device 31 and the slave device 32 are usedto form a piconet 2; meanwhile, the master device 31 is further used toform a piconet 1 with a primary master 33 before the piconet 2 isformed. That is, in forming the piconet 2 the master device 31 alreadyhas a synchronous link with the primary master 33 (e.g., a smartphone orrecording pen shown as Master 1 in FIG. 3) to receive audio signalstherefrom. Accordingly, the initial connection between the master device31 and the slave device 32 is not allowed to use synchronous slotsbetween the master device 31 and the primary master 33. If theconventional paging procedure is used, it may take a longer time to setup the initial connection since fewer time slots are allowed to be usedfor the connection between the master device 31 and the slave device 32.

In the case that the piconet 2 is set up before the piconet 1, the fastpaging procedure of the present disclosure is no longer necessary, i.e.the page substate and the page scan substate mentioned below no longerbeing entered.

The present disclosure is further applicable to a quick point-to-pointlink reconnection if it is lost during streaming.

Referring to FIGS. 4 and 5, they are schematic diagrams of a pagingprocedure of a Bluetooth connection method used in a Bluetooth systemaccording to some embodiments of the present disclosure. It is shownthat the slave device 32 receives a paging message at a firstpredetermined frequency Ch0 (e.g., FIG. 4) or at a second predeterminedfrequency Ch32 (e.g., FIG. 5), and then responds a slave page responsemessage at the first predetermined frequency Ch0 or at the secondpredetermined frequency Ch32.

In step 1, after the inquiry procedure, the master device 31 is in apage substate and the slave device 32 is in a page scan substate. Themaster device 31 repeatedly transmits, e.g., via a Bluetooth antennathereof, a paging message PAGE sequentially (the used frequency beingchanged every 312.5 μs) at multiple predetermined frequencies. Forexample, in FIGS. 4 and 5, a number of the multiple predeterminedfrequencies is set as 2, and said 2 frequencies, e.g., Ch0 and Ch32herein, are set previously and fixed at channels 0 and 32 among 79 radiofrequency (RF) channels of basic piconet physical channels of Bluetooth.However, the present disclosure is not limited thereto, and the 2frequencies are set previously and fixed at channels 16 and 64 or otherpairs among or not among the 79 RF channels of basic piconet physicalchannels of Bluetooth without particular limitations.

To facilitate the initial connection, the multiple predeterminedfrequencies are not calculated or predicted by the master device 31using a Bluetooth device address (BD_ADDR) of the slave device 32, whichis obtained during the last encounter with the slave device 32 or froman inquiry procedure. Preferably, the multiple predeterminedfrequencies, e.g., Ch0 and Ch32 herein, are selected before shipment ofthe master device 31 and the slave device 32 and respectively definedtherein. The paging messages PAGE in FIGS. 4 and 5 are identical andinclude a device access code (DAC) of the slave device 32, which is alsoobtained during the last encounter with the slave device 32 or from aninquiry procedure.

In FIGS. 4 and 5, a paging message PAGE is firstly transmitted atfrequency Ch0 and then transmitted at frequency Ch32 separated by 312.5μs, but the present disclosure is not limited thereto. In anotheraspect, the master device 31 transmits the paging message PAGE atfrequency Ch32 at first and then at frequency Ch0.

Step 2 (also referred to a slave response substate): The slave device 32listens the paging message PAGE at one of the multiple predeterminedfrequencies, e.g., Ch0 and Ch32 herein, for e.g., 1.28 second sent inthe transmit interval of the master device 31, but not limited theretoas long as it is longer than 10 ms. As only two channels are listened,the slave device 32 can quickly receive the paging message PAGE at thechannel thereof. On receiving the paging message PAGE at one frequencyamong the multiple predetermined frequencies, the slave device 32responds, e.g., via a Bluetooth antenna thereof, a slave page responsemessage at said one frequency (i.e. the frequency that the slave device32 receives the paging message PAGE) among the multiple predeterminedfrequencies to the master device 31 in the RX slot of the master device31 in step 2. The slave page response message also contains the deviceaccess code of the slave device 32.

Step 3 (also referred to a master response substate): When receiving theslave page response message in step 2, the master device 31 thentransmits an FHS packet in step 3 to the slave device 32 at the samefrequency receiving the slave page response message. The FHS packetcontains the Bluetooth device address and the clock of the master device31 to be provided to the slave device 32. For example, in FIG. 4 theslave device 32 sends the slave page response message at frequency Ch0in step 2, and then the master device 31 transmits the FHS packet at thefrequency Ch0 in step 3; whereas, in FIG. 5 the slave device 32 sendsthe slave page response message at frequency Ch32 in step 2, and thenthe master device 31 transmits the FHS packet at the frequency Ch32 instep 3.

Step 4 (also referred to slave response substate): After receiving theFHS packet in step 3, the slave device 32 responds in step 4 anotherpage response message (also containing slave's BD_ADDR) at the samefrequency, e.g., Ch0 in FIG. 4 and Ch32 in FIG. 5, receiving the FHSpacket to the master device 31 to acknowledge reception of the FHSpacket.

In step 5, the master device 31 and the slave device 32 both enter aconnection state, and the master device 31 transmits a POLL packet usinga new hopping sequence determined according to a Bluetooth deviceaddress of the master device 31 after receiving the acknowledgementindicating by the another page response message transmitted by the slavedevice 32 in step 4. The determination of the basic channel hoppingsequence is based on the regular setting of Bluetooth communication, andthus details thereof are not described herein.

The time slot of every step from step 1 to step 6 is set as 625 μs.Details of the FHS packet and the POLL packet are known to the art, andthus details thereof are not described herein.

Referring to FIG. 6, it is a schematic diagram of a paging procedure ofa Bluetooth connection method used in a Bluetooth system according toanother embodiment of the present disclosure, in which a slave device 32responds to a paging message at a fourth predetermined frequency. InFIG. 6, a number of the multiple predetermined frequencies (or channels)is set as 4, and the slave device 32 does not respond a slave pageresponse message to the master device 31 at the frequency Ch0, Ch16 orCh32 in this embodiment.

Preferably, in the present disclosure the multiple predeterminedfrequencies are selected equally over the 79 RF channels of basicpiconet physical channels of regular Bluetooth. The reason to separatethe multiple predetermined frequencies as far as possible is to avoidinterference from WiFi signal, noises and other Bluetooth links. Forexample, the 4 frequencies are set previously and fixed at channels 0,24, 48 and 72 among the 79 RF channels of basic piconet physicalchannels of regular Bluetooth, but not limited thereto.

In the case that the multiple predetermined frequencies include morethan 2 frequencies, the master device 31 is arranged to transmit apaging message PAGE sequentially from a first frequency to a lastfrequency (changing every 312.5 μs in TX slots) among the multiplepredetermined frequencies, and the paging message PAGE is transmittedalways starting from the first frequency.

For example, if the first frequency is a lowest frequency among themultiple predetermined frequencies, e.g., Ch0, Ch16, Ch32 and Ch64, themaster device 31 transmits the paging message PAGE starting from thefrequency Ch0, and then transmits the paging message PAGE at frequenciesin a sequence of Ch16, Ch32 and Ch64 every 312.5 μs in TX slots, andrepeatedly in a fixed sequence Ch0, Ch16, Ch32 and Ch64 if no responseis received.

FIG. 6 shows that the master device 31 sequentially transmits the pagingmessage P AGE at frequencies Ch0 and Ch16 in slot 1. If the masterdevice 31 does not receive a response in slot 2 the master device 31further sequentially transmits the paging message PAGE at frequenciesCh32 and Ch64 in slot 3 till a response from the slave device 32 isreceived, e.g., FIG. 6 showing the slave device 32 receives the pagingmessage at the frequency Ch32 in slot 3 and a slave page responsemessage being received at the frequency Ch32 in slot 4. If a response isnot received in slot 4, the master device 31 transmits the pagingmessage PAGE from the frequency Ch0 again in the next slot till thepaging procedure is shut down or a response is received.

On the other hand, if the first frequency is a highest frequency amongthe multiple predetermined frequencies, e.g., Ch0, Ch16, Ch32 and Ch64,the master device 31 transmits the paging message PAGE starting from thefrequency Ch64, and then transmits the paging message PAGE atfrequencies in a sequence of Ch32, Ch16 and Ch0 every 312.5 μs in TXslots, and repeatedly in a fixed sequence Ch64, Ch32, Ch16 and Ch0 if noresponse is received.

In the present disclosure, a start frequency (e.g., the first frequency)is selected from any one of the multiple predetermined frequencies aslong as it is determined previously. A sequence from the start frequencyto the last frequency among the multiple predetermined frequencies is afixed pattern (e.g., from low to high or from high to low) or a randompattern in every fast paging procedure.

Please referring to FIG. 7, it shows that if the master device 31 doesnot receive any response message from the slave device 32, the masterdevice 31 repeatedly transmits the paging message PAGE at the multiplepredetermined frequencies till a response message is received.

In the present disclosure, the paging message PAGE is transmitted alwaysstarting from the first frequency, and the start frequency (e.g. Ch0 inslot 1 of FIGS. 3-6) is not calculated or predicted from any messagereceived from the slave device 32. The slave device 32 either receivesthe paging message PAGE at one of the multiple predeterminedfrequencies, or changes to another frequency every 1.28 μs.

Then, the master device 31 listens a slave page response message in slot4 sent at one of the multiple predetermined frequencies, e.g., Ch64shown in FIG. 6, and then transmits an FHS packet in slot 5 at the samefrequency, e.g., Ch64 shown in FIG. 6, which the slave page responsemessage is sent in slot 4. The slave device 32 responds another pageresponse message in slot 6 to acknowledge reception of the FHS packet.

In slot 7, the master device 31 and the slave device 32 enter aconnection state. The master device 31 transmits a POLL packet as afirst traffic in slot 7, and the slave device 32 responds any type ofpacket to the master device 31 in slot 8 as a response traffic. Asmentioned above, the determination of frequencies of g(m) and g(m+1)utilizes the basic channel hopping sequence based on regular Bluetoothpaging procedure.

It should be mentioned that in the present disclosure, the determinationof whether the master device 31 and slave device 32 receive atransmitted message from the opposite side is identical to the regularBluetooth paging procedure, and thus details thereof are not describedherein.

As mentioned above, in the regular Bluetooth paging procedure, themaster has to estimate the slave's Bluetooth clock and changes thefrequency in different transmit slots based on page hopping sequence.Due to the channel drift of the slave and a large amount of hopingfrequencies and TX slots being used, it may be time consuming to set upa connection. Accordingly, the present disclosure further provides aBluetooth system (e.g., FIG. 3) and a paging method thereof (e.g., FIGS.4-6) that use fewer TX slots and fewer predetermined frequencies notcalculated or predicted from the slave's Bluetooth device address(BD_ADDR) to transmit the paging message, response message and FHSpacket to facilitate the initial connection between the master andslave.

Although the disclosure has been explained in relation to its preferredembodiment, it is not used to limit the disclosure. It is to beunderstood that many other possible modifications and variations can bemade by those skilled in the art without departing from the spirit andscope of the disclosure as hereinafter claimed.

What is claimed is:
 1. A paging method of a master device, performed ina page substate of the master device for connecting to a slave device ina page scan substate, the paging method comprising: repeatedlytransmitting a paging message sequentially from a first frequency to alast frequency among multiple predetermined frequencies in a fixedsequence; listening a slave page response message sent at one of themultiple predetermined frequencies; and transmitting an frequency hopsynchronization (FHS) packet at the one of the multiple predeterminedfrequencies which the slave page response message is listened.
 2. Thepaging method as claimed in claim 1, wherein the paging message and theslave page response message comprise a device access code (DAC) of theslave device.
 3. The paging method as claimed in claim 1, wherein thefirst frequency is a lowest frequency, a highest frequency or anyfrequency among the multiple predetermined frequencies, and a sequencefrom the first frequency to the last frequency is a fixed pattern or arandom pattern.
 4. The paging method as claimed in claim 1, wherein themultiple predetermined frequencies are selected before shipment of themaster device.
 5. The paging method as claimed in claim 1, wherein themultiple predetermined frequencies are not calculated from a Bluetoothdevice address of the slave device.
 6. The paging method as claimed inclaim 1, wherein the multiple predetermined frequencies has a number of2, 4 or 8 frequencies.
 7. The paging method as claimed in claim 6,wherein the 4 frequencies are set previously and fixed at channels 0,16, 32 and 64 or 0, 24, 48 and 72 among 79 RF channels of basic piconetphysical channels of Bluetooth.
 8. A Bluetooth system, comprising: amaster device configured to repeatedly transmit a paging messagesequentially at multiple predetermined frequencies in a fixed sequence;and a slave device configured to receive the paging message and responda slave page response message at one frequency among the multiplepredetermined frequencies, wherein the master device is furtherconfigured to transmit an frequency hop synchronization (FHS) packet tothe slave device at the same frequency receiving the slave page responsemessage.
 9. The Bluetooth system as claimed in claim 8, wherein themaster device is configured as a secondary master and a primary slave,and the master device is further configured to have a synchronous linkwith a primary master.
 10. The Bluetooth system as claimed in claim 8,wherein the master device and slave device are respectively one of apair of earphones.
 11. The Bluetooth system as claimed in claim 8,wherein the paging message and the slave page response message comprisea device access code (DAC) of the slave device.
 12. The Bluetooth systemas claimed in claim 8, wherein the slave device is further configured torespond another page response message to the master device at the samefrequency receiving the FHS packet.
 13. The Bluetooth system as claimedin claim 8, wherein the multiple predetermined frequencies are notcalculated from a Bluetooth device address of the slave device.
 14. TheBluetooth system as claimed in claim 8, wherein the multiplepredetermined frequencies has a number of 2, 4 or 8 frequencies.
 15. TheBluetooth system as claimed in claim 14, wherein the 4 frequencies areset previously and fixed at channels 0, 16, 32 and 64 or 0, 24, 48 and72 among 79 RF channels of basic piconet physical channels of Bluetooth.16. A Bluetooth connection method between a master device and a slavedevice, the method comprising: repeatedly transmitting, by the masterdevice, a paging message sequentially at multiple predeterminedfrequencies to the slave device in a fixed sequence; responding, by theslave device, a slave page response message at one frequency among themultiple predetermined frequencies to the master device; transmitting,by the master device, an frequency hop synchronization (FHS) packet tothe slave device at the same frequency receiving the slave page responsemessage to the slave device; responding, by the slave device, anotherpage response message at the same frequency receiving the FHS packet tothe master device; and transmitting, by the master device afterreceiving the another page response message, a POLL packet using a newhopping sequence determined according to a Bluetooth device address ofthe master device.
 17. The Bluetooth connection method as claimed inclaim 16, wherein the multiple predetermined frequencies are notcalculated from a Bluetooth device address of the slave device.
 18. TheBluetooth connection method as claimed in claim 16, wherein the multiplepredetermined frequencies are selected equally over 79 RF channels ofbasic piconet physical channels of Bluetooth.
 19. The Bluetoothconnection method as claimed in claim 16, wherein the multiplepredetermined frequencies has a number of 2 frequencies, and the 2frequencies are set previously and fixed at channels 0 and 32, atchannels 0 and 24, at channels 16 and 64 or at channels 48 and 72 among79 RF channels of basic piconet physical channels of Bluetooth.
 20. TheBluetooth connection method as claimed in claim 16, wherein the multiplepredetermined frequencies has a number of 4 frequencies, and the 4frequencies are set previously and fixed at channels 0, 16, 32 and 64 or0, 24, 48 and 72 among 79 RF channels of basic piconet physical channelsof Bluetooth.